Mobile wireless communication devices, such as a cellular telephone or a wireless personal digital assistant, can provide a wide variety of communication services including, for example, voice communication, text messaging, internet browsing, and electronic mail. Mobile wireless communication devices can operate in a wireless communication network of overlapping “cells”, each cell providing a geographic area of wireless signal coverage that extends from a radio network subsystem located in the cell. The radio network subsystem can include a base transceiver station (BTS) in a Global System for Communications (GSM) network or a Node B in a Universal Mobile Telecommunications System (UMTS) network. Whether idle or actively connected, a mobile wireless communication device can be associated with a “serving” cell in a wireless communication network and be aware of neighbor cells to which the mobile wireless communication device can also associate. The quality of a communication link between the mobile wireless communication device and the radio network subsystem can vary based on the distance between them and on interference included in received signals at either end of the communication link. As the mobile wireless communication device moves further away from an associated radio network subsystem, eventually a neighbor cell can provide an equal or better performing communication link than the current serving cell. The mobile wireless communication device can include a process for determining if and when to switch cells with which it associates. If the mobile wireless communication device is actively connected to the serving cell, then the process of switching to a neighbor cell is known as “handoff.”
To detect the presence of neighbor cells and to determine an expected quality of communication links to detected neighbor cells, the mobile wireless communication device can listen to messages periodically broadcast by radio network subsystems located in the neighbor cells. Radio network controllers in the wireless communication network can manage handoff of the mobile wireless communication device between different cells based on measurements taken by the mobile wireless communication device when listening to the periodically broadcast messages. In certain wireless communication networks, transmit and receive frequency spectra used by mobile wireless communication device in the serving cell can overlap transmit and receive frequency spectra used in neighbor cells. If the mobile wireless communication device transmits and receives continuously with the network subsystem located in the serving cell, then the mobile wireless communication device can be unable to listen to broadcast messages sent by neighbor cells that occupy the same frequency spectra. In order to suppress transmissions between the mobile wireless communication device and the network subsystem in the serving cell with which the mobile wireless communication device can be associated, network controllers in the wireless network can initiate an operating mode that includes quiet periods during transmissions that can be used for measurement. In a UMTS network using wideband code division multiple access (WCDMA) technology, such a transmission mode is referred to as a “compressed” mode.
A network controller can communicate parameters to the mobile wireless communication device in a network control message that can specify time periods for a “compressed” mode. The network control message can include a time indication for when the mobile wireless communication device and the serving cell's radio network subsystem can start and end. Time indications can be based at least partially on time synchronization counters maintained at the mobile wireless communication device and the radio network subsystem. Because both the serving cell's radio network subsystem and the mobile wireless communication device should enter the “compressed” mode simultaneously, the network control message start time indication can be at a future time, thereby allowing both the serving cell's radio network subsystem and the mobile wireless communication device time to prepare for changing transmission modes. The time required to transmit the entire network control message from the serving cell radio network subsystem to the mobile wireless communication device as a series of discrete packets, however, can be indeterminate. Each discrete packet in the network control message can be corrupted individually during transmission to the mobile wireless communication device and require re-transmission by the radio network subsystem. With sufficient time delays in transmission, the “future” time indication that specifies when to start the “compressed” mode can refer to a “past” time, i.e. the radio network subsystem can enter “compressed” mode before the mobile wireless communication device. Additionally, time synchronization counters maintained at the mobile wireless communication device and the radio network subsystem can be based on a digital counter having a finite length, and thus the time synchronization counters can “roll over” after a period of time. The mobile wireless communication device can interpret the time indications for starting the “compressed” mode as a future time when they actually can indicate a past time. The mobile wireless communication device and the serving cell radio network subsystem can start and end compressed modes at each end of a communication link between them at different times resulting in misaligned compressed mode time intervals and potentially incurring transmission errors. Similar errors can occur for a configuration change message from the serving cell radio network subsystem that includes at least a start time indication based on finite length time synchronization counters.
Thus there exists a need to control configuration time changes between a mobile wireless communication device and a radio network subsystem that accounts for transmission delays and time synchronization counter values.